1. Field of the Invention
This invention is in the field of compositions for introducing controlled amounts of fluoride ions into the circulatory system. The composition of the present invention is a chewing gum containing sodium fluoride and calcium carbonate in the form of oyster shell and provides a novel route for the oral administration of fluoride ions by means of the orobuccal phase.
2. Description of the Prior Art
Extensive studies on the part of the U.S. Public Health Service several decades ago established that the fluoridation of water could be employed as a practical measure to reduce the incidence of tooth decay. It has now been definitely established on the basis of large scale studies in a number of communities that the fluoridation of water to a concentration of 1.0 ppm is a safe and practical public health measure which results in a 50 to 66% reduction in the incidence of dental caries in permanent teeth. There is also evidence to show that the topical application of 2% sodium fluoride to the teeth of children may reduce the incidence of caries as much as 40%.
More recently, it has been demonstrated in a 15-year study that the administration of sodium fluoride in relatively small amounts during pregnancy resulted in an almost complete elimination of dental caries in the subsequently born children. (Glenn, Journal of Dentistry for Children, January, 1980.)
There has also been a disclosure of incorporating sodium fluoride into a chewing gum in the patent art, as evidenced by U.S. Pat. Nos. 2,627,493 and 2,700,012 of Merckel et al. The specifications of the two patents are the same, both dealing with the inclusion of sodium fluoride into chewing gum bases. The problem sought to be overcome by the Merckel et al patents was the interaction of sodium fluoride with calcium compounds, particularly calcium carbonate whether present as an ingredient in the chicle or as a filler. In the '493 patent this was accomplished by dissolving out the calcium compound by means of a strong acid and then washing out the resulting salt. In the '012 patent, the calcium was more or less deactivated by reacting the same with an oxalate, phosphate, or the like which, according to the theory expressed in the specification, immobilized the calcium, preventing its reaction with the sodium fluoride.
The absorption of fluoride ions from the gastrointestinal tract varies considerably. A number of fluoride preparations are available in liquid, gel, compressed tablets, and gelatin capsule encased powders. The testing of such preparations was reported by Deka et al in "The Laryngoscope", Volume 88 (1978). This article reported on the gastric intestinal absorption of five different preparations of sodium fluoride, measured by 10-hour urinary excretion. It was found that the best absorption was by nonenteric coated sodium fluoride. All three enteric coated preparations showed poorer absorption, with marked individual variations. The combination of sodium fluoride and calcium carbonate present in oyster shell showed better absorption than the enteric coated tablets and only slightly less than sodium fluoride alone.